File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

CSV file extension

Comma Separated Values File

Data Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

VOB file extension

DVD Video Object File

Video Files

RA file extension

Real Audio File

Audio Files

MOV file extension

Apple QuickTime Movie

Video Files

TXT file extension

Plain Text File

Text Files

DEB file extension

Debian Software Package

Compressed Files

CFM file extension

ColdFusion Markup File

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

SLN file extension

Visual Studio Solution File

Developer Files

TIFF file extension

Tagged Image File Format

Raster Image Files

NES file extension

Nintendo (NES) ROM File

Game Files

GBR file extension

Gerber File

Data Files